Synthesis of nanocrystalline Spinel phase by Mechanical Milling of Al-Cu-Fe and Al-Cu-Cr-Fe Quasicrystalline alloys

摘要

In the present study, low-temperature synthesis of (Cu Fe)Al2O4 and (Cu CrFe)Al2O4 spinels from the quasicrystalline phases was investigated with thevariation of process parameters during milling and annealing. The milling ofthe quasicrystalline materials was carried out in an attritor mill at 400 rpmfor 40 hours with ball to powder ratio of 40:1 in hexane medium. Subsequently,annealing was performed in an air ambience for 10, 20, and 40 h at 400, 500,600 and 700 C in side a furnace in order to oxidize the mechanically milledquasicrystalline phase for the possible formation of the spinel phase. It wasfound that after annealing at higher temperature (500 C), mechanically milledquasicrystalline alloy transformed to spinel phase whereas annealing at lowertemperature (500 C) it led to the formation of B2 phase as a major one alongwith minor amount of oxide phase. The X-ray diffraction and transmissionelectron microscopy of the annealed samples confirmed the formation of spinelphase with an average grain size of 20-40 nm. It is interesting to note thatthe nanospinel phases showed the different colors during various annealing timeand temperature. The optical properties of nanospinel materials, investigatedemploying UV visible spectrometer exhibited absorption characteristics.